1. Field of the Invention
The present invention relates to a process for the preparation of L-aspartic acid.
2. Description of the Prior Art
Conventionally, L-aspartic acid is obtained from ammonium aspartate which itself is generally prepared via enzymatic treatment of ammonium fumarate. The precipitation of L-aspartic acid from ammonium aspartate is carried out using an inorganic or organic acid which has a pK.sub.a which is less than the corresponding acidity of L-aspartic acid, i.e., less than 3.65. Among the acids commonly used therefor, the inorganic acids are especially representative, more particularly sulfuric acid. Maleic acid can also be used.
However, in this type of precipitation, the production of the ammonium salt of the acid under consideration is observed jointly with the formation of the expected L-aspartic acid. With respect to L-aspartic acid, this byproduct constitutes an impurity which, indeed, must be removed. The corresponding separation stage is undesirable both on an economic level, because it requires additional cost in the process, and on an ecological level, by reason of contamination of effluents.